1 /*-
2 * Copyright (c) 1996 by
3 * Sean Eric Fagan <sef@kithrup.com>
4 * David Nugent <davidn@blaze.net.au>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, is permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice immediately at the beginning of the file, without modification,
12 * this list of conditions, and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. This work was done expressly for inclusion into FreeBSD. Other use
17 * is permitted provided this notation is included.
18 * 4. Absolutely no warranty of function or purpose is made by the authors.
19 * 5. Modifications may be freely made to this file providing the above
20 * conditions are met.
21 *
22 * High-level routines relating to use of the user capabilities database
23 *
24 * $FreeBSD: head/lib/libutil/login_class.c 256850 2013-10-21 16:46:12Z kib $
25 */
26
27 #include <sys/types.h>
28 #include <sys/resource.h>
29 #include <sys/rtprio.h>
30 #include <sys/stat.h>
31 #include <sys/time.h>
32
33 #include <ctype.h>
34 #include <err.h>
35 #include <errno.h>
36 #include <fcntl.h>
37 #include <login_cap.h>
38 #include <paths.h>
39 #include <pwd.h>
40 #include <signal.h>
41 #include <stdio.h>
42 #include <stdlib.h>
43 #include <string.h>
44 #include <syslog.h>
45 #include <unistd.h>
46
47
48 static struct login_res {
49 const char *what;
50 rlim_t (*who)(login_cap_t *, const char *, rlim_t, rlim_t);
51 int why;
52 } resources[] = {
53 { "cputime", login_getcaptime, RLIMIT_CPU },
54 { "filesize", login_getcapsize, RLIMIT_FSIZE },
55 { "datasize", login_getcapsize, RLIMIT_DATA },
56 { "stacksize", login_getcapsize, RLIMIT_STACK },
57 { "memoryuse", login_getcapsize, RLIMIT_RSS },
58 { "memorylocked", login_getcapsize, RLIMIT_MEMLOCK },
59 { "maxproc", login_getcapnum, RLIMIT_NPROC },
60 { "openfiles", login_getcapnum, RLIMIT_NOFILE },
61 { "coredumpsize", login_getcapsize, RLIMIT_CORE },
62 { "sbsize", login_getcapsize, RLIMIT_SBSIZE },
63 { "vmemoryuse", login_getcapsize, RLIMIT_VMEM },
64 #ifdef RLIMIT_POSIXLOCKS
65 { "posixlocks", login_getcapnum, RLIMIT_POSIXLOCKS },
66 #endif
67 { NULL, 0, 0 }
68 };
69
70
71 void
setclassresources(login_cap_t * lc)72 setclassresources(login_cap_t *lc)
73 {
74 struct login_res *lr;
75
76 if (lc == NULL)
77 return;
78
79 for (lr = resources; lr->what != NULL; ++lr) {
80 struct rlimit rlim;
81
82 /*
83 * The login.conf file can have <limit>, <limit>-max, and
84 * <limit>-cur entries.
85 * What we do is get the current current- and maximum- limits.
86 * Then, we try to get an entry for <limit> from the capability,
87 * using the current and max limits we just got as the
88 * default/error values.
89 * *Then*, we try looking for <limit>-cur and <limit>-max,
90 * again using the appropriate values as the default/error
91 * conditions.
92 */
93
94 if (getrlimit(lr->why, &rlim) != 0)
95 syslog(LOG_ERR, "getting %s resource limit: %m", lr->what);
96 else {
97 char name_cur[40];
98 char name_max[40];
99 rlim_t rcur = rlim.rlim_cur;
100 rlim_t rmax = rlim.rlim_max;
101
102 sprintf(name_cur, "%s-cur", lr->what);
103 sprintf(name_max, "%s-max", lr->what);
104
105 rcur = (*lr->who)(lc, lr->what, rcur, rcur);
106 rmax = (*lr->who)(lc, lr->what, rmax, rmax);
107 rlim.rlim_cur = (*lr->who)(lc, name_cur, rcur, rcur);
108 rlim.rlim_max = (*lr->who)(lc, name_max, rmax, rmax);
109
110 if (setrlimit(lr->why, &rlim) == -1)
111 syslog(LOG_WARNING, "set class '%s' resource limit %s: %m", lc->lc_class, lr->what);
112 }
113 }
114 }
115
116
117
118 static struct login_vars {
119 const char *tag;
120 const char *var;
121 const char *def;
122 int overwrite;
123 } pathvars[] = {
124 { "path", "PATH", NULL, 1},
125 { "cdpath", "CDPATH", NULL, 1},
126 { "manpath", "MANPATH", NULL, 1},
127 { NULL, NULL, NULL, 0}
128 }, envars[] = {
129 { "lang", "LANG", NULL, 1},
130 { "charset", "MM_CHARSET", NULL, 1},
131 { "timezone", "TZ", NULL, 1},
132 { "term", "TERM", NULL, 0},
133 { NULL, NULL, NULL, 0}
134 };
135
136 static char *
substvar(const char * var,const struct passwd * pwd,int hlen,int pch,int nlen)137 substvar(const char * var, const struct passwd * pwd, int hlen, int pch, int nlen)
138 {
139 char *np = NULL;
140
141 if (var != NULL) {
142 int tildes = 0;
143 int dollas = 0;
144 char *p;
145 const char *q;
146
147 if (pwd != NULL) {
148 for (q = var; *q != '\0'; ++q) {
149 tildes += (*q == '~');
150 dollas += (*q == '$');
151 }
152 }
153
154 np = malloc(strlen(var) + (dollas * nlen)
155 - dollas + (tildes * (pch+hlen))
156 - tildes + 1);
157
158 if (np != NULL) {
159 p = strcpy(np, var);
160
161 if (pwd != NULL) {
162 /*
163 * This loop does user username and homedir substitutions
164 * for unescaped $ (username) and ~ (homedir)
165 */
166 while (*(p += strcspn(p, "~$")) != '\0') {
167 int l = strlen(p);
168
169 if (p > np && *(p-1) == '\\') /* Escaped: */
170 memmove(p - 1, p, l + 1); /* Slide-out the backslash */
171 else if (*p == '~') {
172 int v = pch && *(p+1) != '/'; /* Avoid double // */
173 memmove(p + hlen + v, p + 1, l); /* Subst homedir */
174 memmove(p, pwd->pw_dir, hlen);
175 if (v)
176 p[hlen] = '/';
177 p += hlen + v;
178 }
179 else /* if (*p == '$') */ {
180 memmove(p + nlen, p + 1, l); /* Subst username */
181 memmove(p, pwd->pw_name, nlen);
182 p += nlen;
183 }
184 }
185 }
186 }
187 }
188
189 return (np);
190 }
191
192
193 void
setclassenvironment(login_cap_t * lc,const struct passwd * pwd,int paths)194 setclassenvironment(login_cap_t *lc, const struct passwd * pwd, int paths)
195 {
196 struct login_vars *vars = paths ? pathvars : envars;
197 int hlen = pwd ? strlen(pwd->pw_dir) : 0;
198 int nlen = pwd ? strlen(pwd->pw_name) : 0;
199 char pch = 0;
200
201 if (hlen && pwd->pw_dir[hlen-1] != '/')
202 ++pch;
203
204 while (vars->tag != NULL) {
205 const char * var = paths ? login_getpath(lc, vars->tag, NULL)
206 : login_getcapstr(lc, vars->tag, NULL, NULL);
207
208 char * np = substvar(var, pwd, hlen, pch, nlen);
209
210 if (np != NULL) {
211 setenv(vars->var, np, vars->overwrite);
212 free(np);
213 } else if (vars->def != NULL) {
214 setenv(vars->var, vars->def, 0);
215 }
216 ++vars;
217 }
218
219 /*
220 * If we're not processing paths, then see if there is a setenv list by
221 * which the admin and/or user may set an arbitrary set of env vars.
222 */
223 if (!paths) {
224 const char **set_env = login_getcaplist(lc, "setenv", ",");
225
226 if (set_env != NULL) {
227 while (*set_env != NULL) {
228 char *p = strchr(*set_env, '=');
229
230 if (p != NULL) { /* Discard invalid entries */
231 char *np;
232
233 *p++ = '\0';
234 if ((np = substvar(p, pwd, hlen, pch, nlen)) != NULL) {
235 setenv(*set_env, np, 1);
236 free(np);
237 }
238 }
239 ++set_env;
240 }
241 }
242 }
243 }
244
245
246
247 /*
248 * setclasscontext()
249 *
250 * For the login class <class>, set various class context values
251 * (limits, mainly) to the values for that class. Which values are
252 * set are controlled by <flags> -- see <login_class.h> for the
253 * possible values.
254 *
255 * setclasscontext() can only set resources, priority, and umask.
256 */
257
258 int
setclasscontext(const char * classname,unsigned int flags)259 setclasscontext(const char *classname, unsigned int flags)
260 {
261 int rc;
262 login_cap_t *lc;
263
264 lc = login_getclassbyname(classname, NULL);
265
266 flags &= LOGIN_SETRESOURCES | LOGIN_SETPRIORITY |
267 LOGIN_SETUMASK | LOGIN_SETPATH;
268
269 rc = lc ? setusercontext(lc, NULL, 0, flags) : -1;
270 login_close(lc);
271 return (rc);
272 }
273
274
275
276 /*
277 * Private function which takes care of processing
278 */
279
280 static mode_t
setlogincontext(login_cap_t * lc,const struct passwd * pwd,mode_t mymask,unsigned long flags)281 setlogincontext(login_cap_t *lc, const struct passwd *pwd,
282 mode_t mymask, unsigned long flags)
283 {
284 if (lc) {
285 /* Set resources */
286 if (flags & LOGIN_SETRESOURCES)
287 setclassresources(lc);
288 /* See if there's a umask override */
289 if (flags & LOGIN_SETUMASK)
290 mymask = (mode_t)login_getcapnum(lc, "umask", mymask, mymask);
291 /* Set paths */
292 if (flags & LOGIN_SETPATH)
293 setclassenvironment(lc, pwd, 1);
294 /* Set environment */
295 if (flags & LOGIN_SETENV)
296 setclassenvironment(lc, pwd, 0);
297 }
298 return (mymask);
299 }
300
301
302
303 /*
304 * setusercontext()
305 *
306 * Given a login class <lc> and a user in <pwd>, with a uid <uid>,
307 * set the context as in setclasscontext(). <flags> controls which
308 * values are set.
309 *
310 * The difference between setclasscontext() and setusercontext() is
311 * that the former sets things up for an already-existing process,
312 * while the latter sets things up from a root context. Such as might
313 * be called from login(1).
314 *
315 */
316
317 int
setusercontext(login_cap_t * lc,const struct passwd * pwd,uid_t uid,unsigned int flags)318 setusercontext(login_cap_t *lc, const struct passwd *pwd, uid_t uid, unsigned int flags)
319 {
320 rlim_t p;
321 mode_t mymask;
322 login_cap_t *llc = NULL;
323 struct rtprio rtp;
324
325 if (lc == NULL) {
326 if (pwd != NULL && (lc = login_getpwclass(pwd)) != NULL)
327 llc = lc; /* free this when we're done */
328 }
329
330 if (flags & LOGIN_SETPATH)
331 pathvars[0].def = uid ? _PATH_DEFPATH : _PATH_STDPATH;
332
333 /* we need a passwd entry to set these */
334 if (pwd == NULL)
335 flags &= ~(LOGIN_SETGROUP | LOGIN_SETLOGIN);
336
337 /* Set the process priority */
338 if (flags & LOGIN_SETPRIORITY) {
339 p = login_getcapnum(lc, "priority", LOGIN_DEFPRI, LOGIN_DEFPRI);
340
341 if (p > PRIO_MAX) {
342 rtp.type = RTP_PRIO_IDLE;
343 p -= PRIO_MAX + 1;
344 rtp.prio = p > RTP_PRIO_MAX ? RTP_PRIO_MAX : p;
345 if (rtprio(RTP_SET, 0, &rtp))
346 syslog(LOG_WARNING, "rtprio '%s' (%s): %m",
347 pwd ? pwd->pw_name : "-",
348 lc ? lc->lc_class : LOGIN_DEFCLASS);
349 } else if (p < PRIO_MIN) {
350 rtp.type = RTP_PRIO_REALTIME;
351 p -= PRIO_MIN - RTP_PRIO_MAX;
352 rtp.prio = p < RTP_PRIO_MIN ? RTP_PRIO_MIN : p;
353 if (rtprio(RTP_SET, 0, &rtp))
354 syslog(LOG_WARNING, "rtprio '%s' (%s): %m",
355 pwd ? pwd->pw_name : "-",
356 lc ? lc->lc_class : LOGIN_DEFCLASS);
357 } else {
358 if (setpriority(PRIO_PROCESS, 0, (int)p) != 0)
359 syslog(LOG_WARNING, "setpriority '%s' (%s): %m",
360 pwd ? pwd->pw_name : "-",
361 lc ? lc->lc_class : LOGIN_DEFCLASS);
362 }
363 }
364
365 /* Setup the user's group permissions */
366 if (flags & LOGIN_SETGROUP) {
367 if (setgid(pwd->pw_gid) != 0) {
368 syslog(LOG_ERR, "setgid(%lu): %m", (u_long)pwd->pw_gid);
369 login_close(llc);
370 return (-1);
371 }
372 if (initgroups(pwd->pw_name, pwd->pw_gid) == -1) {
373 syslog(LOG_ERR, "initgroups(%s,%lu): %m", pwd->pw_name,
374 (u_long)pwd->pw_gid);
375 login_close(llc);
376 return (-1);
377 }
378 }
379
380 /* Set the sessions login */
381 if ((flags & LOGIN_SETLOGIN) && setlogin(pwd->pw_name) != 0) {
382 syslog(LOG_ERR, "setlogin(%s): %m", pwd->pw_name);
383 login_close(llc);
384 return (-1);
385 }
386
387 mymask = (flags & LOGIN_SETUMASK) ? umask(LOGIN_DEFUMASK) : 0;
388 mymask = setlogincontext(lc, pwd, mymask, flags);
389 login_close(llc);
390
391 /* This needs to be done after anything that needs root privs */
392 if ((flags & LOGIN_SETUSER) && setuid(uid) != 0) {
393 syslog(LOG_ERR, "setuid(%lu): %m", (u_long)uid);
394 return (-1); /* Paranoia again */
395 }
396
397 /*
398 * Now, we repeat some of the above for the user's private entries
399 */
400 if (getuid() == uid && (lc = login_getuserclass(pwd)) != NULL) {
401 mymask = setlogincontext(lc, pwd, mymask, flags);
402 login_close(lc);
403 }
404
405 /* Finally, set any umask we've found */
406 if (flags & LOGIN_SETUMASK)
407 umask(mymask);
408
409 return (0);
410 }
411